RU2766998C1 - Universal testing machine for mechanical tests of samples of materials and articles for tension, compression and bending at static load application and for low- and high-cycle fatigue at tension-compression at cyclic load application at normal and high temperatures - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to means (testing machines) and methods of mechanical tests of samples of materials for tension, compression, bending and for low- and high-cycle fatigue. Testing machine comprises a loading device comprising a base, two worm-and-screw reduction gears attached to the base and connected to each other by a coupling, a servo motor driving the cross-arm using worm-and-screw gearboxes and nuts coupled with screws and fixed in traverse, housing nuts coupled with lead screws, with built-in annular pistons for sampling play between screws and traverse, guide columns fixed in the base and coupled with the traverse through the ball bushings, the cross bar rigidly connecting the guide columns and the lead screws through the ball bearings, a hydraulic cylinder formed by the traverse, a plunger and two flanges, upper grip attached to the plunger by means of a pin and two hinged joints, a displacement sensor, a force sensor attached to the base by means of a pin and two hinged joints, a lower grip, attached to the force sensor by means of a pin, a rack for installation of the furnace during high-temperature tests, attached to the base and the crossbar, and also includes a pump unit and a control and measurement system. Machine has two test specimen loading drives: servo-mechanical - by movement of crossbar with upper gripper and servo-hydraulic - by movement of upper grip relative to crosshead with the help of hydraulic cylinder built in crossbar.

EFFECT: technical result is the ability to test samples and large-length articles with a large deformation value during static application of a load, the ability to test samples for tension, compression, bending, low- and high-cycle fatigue with any coefficient of asymmetry of the cycle, possibility of applying a high-frequency component to the static component of the cycle, simplification and cheapening of the design of the loading device.

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Description

There are machines for this purpose, in which the hydraulic cylinder performs the functions of static and cyclic loading, and the height of the working space is regulated by moving the traverse with grippers along smooth columns with additional hydraulic cylinders and fixing it on the columns with collet clamps (for example, machines of the MIU type, manufactured by NIKTSIM Tochmashpribor LLC jointly with the ZIM plant in Armavir).

There are also machines (mostly foreign-made), in which the height of the working space is set by moving the traverse along the threaded columns, and the hydraulic cylinder also performs the loading function.

In terms of purpose and functionality, the MIU type machines are closest to the claimed one and can be taken as a prototype (analogue).

The disadvantages of the analogue include the fact that with a relatively complex design of the loading device, it is impossible to test products of great length with a large amount of deformation under static loading on the machine due to the limitation of the stroke of the power-exciting hydraulic cylinder.

These shortcomings are deprived of the claimed machine.

The attached drawings (Fig. 1, 2) show the inventive machine, which includes the following nodes:

- loading device I, designed to deform the test specimen;

- pumping unit II, which ensures the operation of the servo-hydraulic loading system;

- control system;

- measurement system.

Loading device I contains:

- base 1 (Fig. 1), two worm gearboxes 2 fastened to the base and interconnected by a coupling 3, a servomotor 4 that drives the lead screws 5 of the gearboxes, a force sensor 6 fastened to the base 1 using a pin 7 with two articulated nodes 8, the lower grip 9, fastened to the force sensor using a pin 10, the upper grip 11, fastened to the plunger 12 using a pin 13 with two hinge nodes 14 built into the plunger 12, the cuff 15, the sealing cavity "A", the movable traverse 16, flange 17, which forms a hydraulic cavity “B” with plunger 12 and traverse 16, two nuts 18 (Fig. 2, view D) fastened to traverse 16 and articulated with screws 5, two backlash sampling mechanisms between screws 5 and traverse 16 , including thrust bushings 19, nuts-housings 20, pins 21 from rotation of nuts-housings 20, annular pistons 22, forming with nuts-housings 20 hydraulic cavities "B" (Fig. 2, section K-K), the cross-sectional area of \u200b\u200bwhich in total exceeds by 5 ... 10% the area of the cavity "B" of the hydraulic cylinder, the flange 23, which forms the cavity "A" with the traverse 16 and the plunger 12, the displacement sensor 24 (Fig. 2, section E-E) of the capture 11 relative to the traverse 16, two columns 25, fastened to the base 1 with nuts 26, guide ball bushings 27, articulating columns 25 with the traverse 16 and held in the traverse by flanges 28, the cross member 29 associated with the lead screws 5 through a ball bearing 30 and a flange 31 and fastened with columns 25 with screws 32 and flanges 33, a servo valve 34 fastened with a flange 23, which serves to control the process of loading the sample (product), as well as to control the installation stroke of the gripper 11 relative to the traverse 16.

Hydraulic cylinder built into traverse 16 - differential:

cavity "B" (Fig. 2, section E-E) is under constant pressure of the high pressure line, cavity "A" is controlled by a servo valve 34 (Fig. 2, view D), which supplies from the high pressure line to the cavity "A" ( Fig. 2, section G-Zh) and draining the working fluid from cavity "A" into tank 42 (Fig. 2, section II-I).

The area of the rod cavity "B" is two times less than the area of the piston cavity "A".

To install the furnace during high-temperature tests, a rack 36 is attached to the base 1 using clamps 35, articulated with the crossbar 29 through the bar 37, fastened to the crossbar with screws 38 and pins 39.

Pumping unit II contains:

- high-capacity pump 40 with electric motor 41;

- tank 42 for placing the working fluid;

- low-capacity pump 43 with electric motor 44;

- safety valve 45 to maintain the set pressure in the high pressure line;

- pressure gauge 46 to control the pressure in the high pressure line;

- hydrodistributors 47 and 48 for control of captures;

- hydraulic distributor 49 for turning on and off the mechanism for fixing the traverse 16 relative to the lead screws;

- check valves, filters, faucet.

The claimed machine works as follows:

1. When testing a sample using a servomechanical

drive.

The test sample is loaded by moving the traverse 16 with a fixed plunger 12 using a servomotor 4 and worm-screw gearboxes 2. To test the sample, do the following:

- turn on low-capacity pump 43 and use valve 45 to adjust the pressure in the high-pressure line, which creates a force in cavity “B” on plunger 12 that exceeds the expected maximum load on the sample by 10 ... 15%;

- using the servo valve 34, set the plunger 12 to the extreme upper position, pressing the end of the plunger 12 to the end of the flange 23;

- using the servomotor 4 to set the height of the working space, corresponding to the length of the test sample, by moving the traverse 16 along the lead screws 5;

- install the control sample in the grips and fix it with the help of distributors 47 and 48, while, if necessary, manipulating the position of the traverse 16 using the servomotor 4;

- using a servomotor 4, load the installed sample for tension, exceeding the limit by 10 ... 15% and tighten the nuts of the lower hinge assembly 8 and the upper hinge assembly 14;

- unload the machine, remove the control and install the test sample in the grips;

- to test the sample for tension, loading it according to a given program using a servomotor 4 and a control system with recording the test results on a diagram in the coordinates "load-displacement", "load-strain" (when testing with a strain gauge on the sample);

- perform compression and bending tests by installing appropriate devices on the grips (see patent No. 2678935).

2. When testing a sample using a servo-hydraulic drive.

The test sample is loaded using a hydraulic cylinder built into the traverse 16.

To test a sample, you must:

- turn on pump 43 of low capacity;

- set the required pressure in the high pressure line (see the previous section);

- using the servo-hydraulic control system, using the displacement sensor 24 (Fig. 2, section E-E), set the height of the cushion in the cavity "A" ~ 5 ... 10 mm (distance from the end of the plunger 12 to the end of the flange 23);

- using the servomotor 4, set the distance between the grips, corresponding to the length of the test sample;

- using a hydraulic distributor 49, connect the cavities "B" (Fig. 2, section K-K) of the mechanisms for sampling the backlash between the nuts 18 and the lead screws 5 with the high pressure line;

- turn on the high-capacity pump 40, "correct" the pressure in the high-pressure line with valve 45, turn off the low-capacity pump 43;

- by controlling cavity "A" with the help of servo valve 34, test the sample for cyclic fatigue under alternating loading according to a given program, as well as tests for tension, compression and bending (see the previous section);

- in the process of testing the sample, record diagrams in the coordinates "load-time", "displacement (deformation)-time", and when testing for low-cycle fatigue, record the hysteresis loop according to GOST25.502.

The essence of the invention is as follows.

Unlike analogue, as well as existing universal testing machines of domestic and foreign production, the claimed machine has two servo loading of the test sample (product):

- servomechanical for testing samples (products) in a wide range of lengths (up to several meters) with a static load applied using a servomotor;

- servo-hydraulic for testing samples in static, low-cycle and high-cycle loading modes using a hydraulic cylinder built into the movable traverse.

This gave the following result:

- the ability to test samples and products of great length with a large amount of deformation (working stroke up to several meters) with a static load application using a servo-mechanical loading drive;

- the ability to test samples for tension, compression, bending, low- and high-cycle fatigue with any cycle asymmetry coefficient using a servo-hydraulic loading drive;

- the ability to impose a high-frequency component on the static component of the cycle with simultaneous operation of both loading drives;

- the combination of the hydraulic cylinder with the traverse simplified and reduced the cost of the design of the loading device.

Claims (2)

1. Universal testing machine for mechanical testing of samples of materials and products for tension, compression and bending under static load application for low- and high-cycle tensile-compression fatigue, under cyclic load application, at normal and elevated temperatures, including a loading device containing a base , two worm-screw gearboxes fastened to the base and interconnected by a coupling, a servo motor that drives the traverse using worm-screw gearboxes and nuts associated with screws and fixed in the traverse, housing nuts articulated with lead screws, with built-in in them, annular pistons for sampling the backlash between the screws and the traverse, guide columns fixed at the base and coupled with the traverse through ball bushings, a cross member rigidly connecting the guide columns and lead screws through ball bearings, a hydraulic cylinder formed by the traverse, a plunger and two flanges, an upper grip , fastened with a plunger using a pin and two hinge assemblies, a displacement sensor, a force sensor fastened to the base with a pin and two hinge assemblies, a lower grip fastened to a force sensor with a pin, a rack for installing a furnace for high-temperature tests, fastened to the base and a crossbar, as well as including a pumping unit and a control and measurement system, characterized in that the machine has two drives for loading the test sample: servo-mechanical - by moving the traverse with the upper grip and servo-hydraulic - by moving the upper grip relative to the traverse using a hydraulic cylinder built into the traverse . 2. The test machine according to claim 1, characterized in that the traverse is the body of the hydraulic cylinder, and the pin with two hinged nodes, with which the upper grip is fastened, is located inside the hydraulic cylinder plunger.

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